(a) Field of the Invention
This invention generally relates to a snap hook with an improved gate mechanism that allows the gate to be loaded in hoop stresses as compared to shear or conventional two-dimensional loads.
(b) Discussion of Known Art
Snap hooks with locking gates that prevent the undesired and unintentional disengagement of the connecting hardware have been used for decades in combination with lanyards for fall protection of workers. However, a limitation of known devices has been inefficient design of the locking gates and the manner of cooperation of the locking gate with the body of the hook to resist external loads, especially loads that are directed to the side (normal to the direction of opening) the gate and to the “top” (in the direction of opening) of the gate. The gate of the snap hook has to be able to resist external loads without opening or resulting in failure by exceeding the strength of the material that comprises the gate. Thus the need for greater safety has been identified by industry, and as a result ANSI (American National Standards Institute) standards have been adopted to address this issue. Previously, gate top and side load strength of snap hooks were developed as an OSHA (Occupational Safety and Health Administration) standard, which allowed these loads to be just under 350 pounds. Under the new, ANSI, regulations the gates must be able to withstand a minimum of 3500 pounds of side and top load.
While it is possible to increase the strength of components by merely making them thicker, that is by adding material. This approach does not always work, particularly with the design of the gate on a highly stressed snap hook. The thickening of the gate results in less space for the structure of the hook itself, or results in a much larger, heavier hook, which is more difficult to carry and use by workers that must carry and use these hooks while attached to lanyards.